NavList:

Howard

I found what I was looking for re: the U-Boat Gyro sextant.  It can be found here: 

http://fer3.com/arc/imgx/arl-report-gyro-sextant-plath.pdf . 

I'm not sure who put it on NavList, maybe me, maybe not.  The little grey cells are getting a bit jaded these days.  Below is what they say about the Rotor (my embolding).  You can also see how close the rotor ran to its casing, which must have meant it was tricky to handle climbing around a U-Boat.  DaveP

(d) GYRO (See Drawing 4) Rotor. The body (1) of this is an aluminum alloy die casting, with the brass rim (2) pressed onto it, and the aluminum alloy tube (3) pressed into it. The brass spindle (4) is screwed into the body and locked with a nut at its upper end. Into its lower end is spun a ball, 1 mm dia. of hardened steel, which bears on the cup (5) The graticule (6) and lens (7) are fixed in the tube (3). 35 buckets, roughly semi-circular, are milled into the circumference of the brass rim. The rotor is bottom heavy.